1. Field of Invention
The present invention relates generally to surgical devices. More particularly, the present invention relates to surgical punch devices for the formation of well-defined holes in blood vessel walls (or other internal bodily tissue layers) during the course of a surgical procedure. Still more particularly, the present invention relates to improvements in surgical punch devices that reduce the levels of applied force required to punch out tissue plugs from tissue walls, and that otherwise improve the operational characteristics of the device.
2. Summary of the Prior Art
Surgical punch devices for forming holes through bodily tissue layers during the course of surgical procedures per se are generally well known in the art. Representative examples of some of the various versions of known surgical punch devices are shown in the following United States Patents (the disclosures of which are hereby incorporated by reference into this specification): U.S. Pat. Nos. 4,018,228; 4,216,776; 5,129,913; 5,192,294; 5,403,338; 5,488,958; and 5,827,316.
The basic concept of surgical punch devices is to provide a device including a pair of externally operable, reciprocally interacting, elongate elements for the formation of a hole through an internal tissue layer at an internal surgical site easily and simply during the course of a surgical procedure. The devices heretofore utilized to accomplish this goal typically included an elongate outer sheath having a distally facing sharpened edge, and an elongate plunger-like member disposed within the outer sheath. The plunger-like member was designed for the reciprocating movement of its distal end from a normally extended position relative to the sharpened edge of the outer sheath into the distal portion of the outer sheath in response to external manipulation of an activation mechanism associated with the proximal portions of the outer sheath and the plunger-like member respectively. The plunger-like member also typically included structure designed to receive tissue while its distal end portion was extended out of the distal end of the outer sheath. Further, the plunger-like member was contemplated to fit tightly enough within the outer sheath that received tissue could be caused to be sheared away from the adjoining tissue layer as the plunger-like member was caused to move past the distally facing sharpened edge of, and into, the outer sheath by the external activation mechanism. (Obviously, the relative movement of the outer sheath and the plunger-like member just described also could be considered as the outer sheath moving relative to the plunger-like member, or as the outer sheath and the plunger-like member moving simultaneously in opposite directions relative to each other without changing the basic operational characteristics of the device.)
Various structural modifications also have been provided to this basic surgical punch device in the prior art.
For example, the outer sheath and the plunger-like member have been interconnected with one another in various ways so as to cause them to rotate relative to each other as they are moved from the normal plunger extended position to the plunger retracted position, and vice versa. This modification introduces a slicing component to the cutting out of a section of a tissue layer contemplated by the basic surgical punch concept. The purpose of this modification is to reduce the level of applied force required to remove a cut out tissue portion (plug) from its adjoining tissue layer.
Further, numerous activation mechanisms for causing the desired relative movement between the outer sheath and inner plunger have been proposed with varying degrees of success. In addition, it is common in surgical punch devices to use a separate cutting blade mounted at the distal end of the outer sheath to provide the distally facing cutting edge, instead of simply sharpening the distal end of the outer sheath. Other modifications of the basic surgical punch device are described in the above-referred-to United States Patents and/or will become apparent as the present discussion proceeds.
A typical example of the heretofore known structure and use of surgical punch devices will be better understood with reference to the following brief discussion of the procedures and requirements of coronary by-pass surgery. It is to be understood, however, that this usage context is presented herein by way of illustrative example only, and that surgical punch devices may, and do, find other usage contexts satisfying other specific requirements.
The goal in coronary by-pass procedures is to create an open blood flow passageway around one or more diseased, blocked or partially occluded coronary arteries so as to ensure appropriate blood flow to the heart muscle. Without such blood flow, the heart muscle may be damaged and/or cease to function appropriately. Hence, if the condition is not corrected, the result may be a heart attack or, in extreme cases, death to the patient.
To accomplish the desired by-pass, it is conventional to use a saphenous vein graft to create an alternative pathway for the flow of blood to the heart muscle. Specifically, an opening (i.e., hole) is formed in the wall of the ascending aorta. Thereafter, the proximal end wall of the graft is anastomosed (attached) around the periphery of the opening in a tight, sealing manner (typically by suturing). The distal end of the graft is then affixed in a similar manner to the periphery of a hole formed in the subject artery downstream from the diseased portion, blockage or occlusion.
The formation of the desired openings in the walls of the involved blood vessels (as parenthetically suggested above) must be understood as involving the creation of open holes in the blood vessel walls. The reasons for this are clear to those skilled in the art. It is only by the formation of open holes that an unobstructed flow of blood through the graft can be insured. The creation of slits, cuts, punctures or the like are not satisfactory. This is primarily because internal bodily tissue demonstrates a tendency to close in upon itself after the passage of a knife-like blade or awl-like device through it. Therefore, it is only by the actual removal of tissue from the blood vessel wall that the presence of a continuously open passageway may be assured.
Accordingly, it has become conventional in the art that the formation of the desired openings (holes) through the blood vessel walls involves the creation of xe2x80x9cpilot openingxe2x80x9d, i.e., a small, slit-like cut or opening through the tissue of the blood vessel wall, often using either a scalpel or scissors. Thereafter, a surgical punch device typically is used to form the desired well-defined hole in the blood vessel wall. This procedure has been found to facilitate the attachment of grafts to blood vessel walls in the desired relationship. It also has been found to aid in the avoidance of complications such as leakage from the attachment site and/or the presence of loose tissue pieces within the hole and/or adjoining blood vessel lumens that could break away and be carried in the bloodstream causing damage or blockages elsewhere within the patient. It also facilitates the removal of punched out tissue from the interior of the patient.
An illustrative version of a conventional surgical punch useful in surgical procedures of the type just summarized is illustratively shown in FIG. 1. Generally speaking, the surgical punch 2 includes an anvil or other support portion 4 formed and/or located at the distal end 6 of a core member (rod) 8. The core member 8 in turn is disposed in telescoping, and generally co-axial, engagement within a generally cylindrical member (outer sheath) 10. Accordingly, the surgical punch may be very much syringe-like in appearance.
Further, while the internal linkage mechanisms inherent in surgical punch devices are different from a common syringe (i.e., distal pushing on the proximal end of the plunger while pulling on finger engagement elements moves the plunger proximally relative to the outer sheath instead of distally relative thereto) the external operating characteristics thereof are very similar to the well-known syringe. Therefore, since conventional surgical punch devices may be operated by a surgeon in much the same manner as a common syringe, and since such devices also produce readily predictable reactions at their distal ends in direct correspondence to applied movements to the parts at their respective proximal ends, conventional surgical punch devices have found ready acceptance in the art.
In addition, with the core member 8 in its normal distalmost position relative to the outer sheath 10, the anvil or support 4 is adapted for insertion into the blood vessel (such as, for example, the aorta) through the small opening formed in the tissue defining its wall by the scalpel or scissors referred to above. Then, as will appear more fully below, the part of the aorta wall surrounding the original cut (xe2x80x9cpilot openingxe2x80x9d) lodges itself in the recessed portion 12 in the core member (rod) 8 located between the anvil 4 and the proximally extending main part 16 of the core member (rod) 8. (See, FIG. 2)
The surgeon then grasps the surgical punch 2 in much the same manner as he/she would grasp a conventional syringe. Thereafter, when he/she approximates his/her thumb and first and second fingers the result is the exertion of a pushing force on a thumb button 18 and the exertion of a pulling force on the finger support 20. This interaction between the surgeon""s hand and the surgical punch device 2 causes the distal end 6 of the core member (rod) 8 to move proximally into the substantially cylindrical member (outer sheath) 10 at its sharpened distal end (blade edge) 22. The desired result of this manipulation is that tissue trapped in the recessed area 12 is sheared away from the adjoining blood vessel (aortal) wall leaving a plug of tissue within the device. The surgical punch device then may be removed from the patient leaving a comparatively large and well-defined hole in the blood vessel (aortal) wall.
Numerous problems remain, however. For example, the tissue of the aorta wall consists of three layers as generally shown in FIG. 2, one of which (known as the xe2x80x9cadventitiaxe2x80x9d) 24 being notoriously fibrous and resilient in nature. Therefore, the tissue of the aorta wall is difficult to sever by shearing cleanly, smoothly and without the need for the application of significant force. More specifically, it will be readily apparent that the shearing of a fibrous and resilient tissue layer along the entire circumference of a hole to be formed therein at the same time is difficult.
One reason for this is that the fit between the cutting edge 22 and the rod 8 typically cannot be made tight enough to assure that the blade rides directly against the outer surface of the rod. In practice, a small gap must be present between the sheath and the outer surface of the rod. This gap is necessary in order to assure that the rod rides satisfactorily in reciprocally movable relation within the sheath. It also is necessary in order to assure that the alignment of the axis of the surgical punch with the tissue wall to be punched can be made as close to perpendicular as possible.
The presence of this gap, on the other hand, allows an undesirable stretching of the fibrous and resilient tissue between the sheath and the rod prior to its being cut by the blade. Therefore, it will recognized that conventional surgical punch devices introduce inconvenient operational distractions during delicate heart surgery and/or similar procedures that may adversely impact the ultimate surgical result. It also has been found that when conventional surgical punch devices are used, there is a tendency for the edges of the hole in the target tissue formed by the punch device to be either rough or frayed (at least microscopically). As mentioned, rough or frayed hole edges can lead to leakage at the joinder of the graft to the aortal wall and/or to the undesirable breakaway of loose material from the aortal wall with resultant potentially problematic conveyance of the same in the bloodstream.
Further, if the tightness of the fit is too great, the result is that the surgeon is faced not only with overcoming the toughness and resilience of the tissue being punched, but also the frictional engagement of the core and the cutting blade. If the tightness of the fit is too loose, however, the tough and resilient nature of the aorta wall tends to stretch the tissue between the cutting blade edge and the outer edge of the distal end of the recessed portion of the core. The resultant definition of the boundary of the hole so formed consequently is not fine in nature, and the applied force required to form the punch out is substantial. In addition, binding between the outer sheath and the rod can become an issue in some cases due to the non-co-axial alignment of their axes of movement relative to one another.
To date, several alternatives have been presented in the art attempting to deal with the foregoing problematic issues. In one of these alternatives (already mentioned), a relative rotation between the cutting blade (outer sheath) and the core (rod) is created as they are moved in opposite directions relative to each other. This results in the hole in the blood vessel wall being formed by more of a circumferential slicing motion of the parts than by a perpendicular shearing action between the parts. This alternative in some cases may improve the smoothness of the hole walls, but at the same time, it undesirably increases in the complexity and cost of the required activation mechanism.
Serrations also have been added to the cutting edge to facilitate the cutting action. The result, however, is a rougher hole edge with little significant improvement in the overall operative characteristics of the device.
Another alternative (illustratively depicted in FIG. 3) that has been utilized in the prior art involves allowing the longitudinal axis of a cutting blade element mounted at the distal end of the outer sheath to xe2x80x9cfloatxe2x80x9d (i.e., to shift slightly longitudinally, radially and/or both simultaneously) relative to the longitudinal axis of the outer sheath. This alternative has the advantage of tending to allow the cutting edge of the cutting blade element to xe2x80x9cfind its own centerxe2x80x9d with regard to the anvil or support as the distal end of the core is being retracted into the cutting blade/outer sheath to punch out a tissue plug. There are detrimental trade offs, however.
For example, the elongate core, generally indicated at 40, is commonly formed of rigid material such as metal, and as a single piece. This core typically extends through the outer sheath 42 that in turn carries a cylindrical cutting blade 44 rigidly affixed to the outer sheath co-axially at its distal end 48. Alternatively, the core of some surgical punches have been formed by a plastic core portion 50 located within the outer sheath 42 and a machined metallic distal core portion 52 insert molded to the distal end 54 of the plastic core 50. When this is done, at least one circumferential recess 56 is typically formed in the machined metallic core portion 52 distally of its proximal end 58 in order to assure a firm and rigid attachment of the plastic and metallic core portions.
Of course, in the latter alternative, the anvil and adjacent distal recessed structure are formed in the machined metallic core portion that extends through the cutting blade 44. In either event, the distal end surface 60 of the outer sheath 42 may be designed to include first, second and third counterbores 62, 64 and 66, respectively, of successively decreasing depth and successively increasing diameter. This configuration, in combination with an end ring cap 68, allows the cutting blade 44 to xe2x80x9cfloatxe2x80x9d relative to the outer sheath 42 in the manner shown in FIG. 3.
The longitudinally hollow cutting blade 44 includes a distally pointed end section 70, a substantially constant diameter proximal section 72, and a mid-section 74 having a diameter larger than the diameter of either the proximal section or the distal section so as to form what may be loosely referred to as an outwardly projecting belt or ridge around the cutting blade 44. The lengths and diameters of the various portions of the cutting blade 44, and of the respective counterbores 62, 64 and 66 are related to each other in such a way that the cutting blade 42 xe2x80x9cfloatsxe2x80x9d within the distal end 60 of the sheath 44 when the ring cap member 68 is inserted proximally into the disalmost counterbore 66.
More specifically, the diameter of counterbore 60 is slightly greater than the diameter of the proximal section 72 of the cutting blade 44, and the length of the counterbore 60 is slightly greater than the combined length of the proximal section 72 and mid section 74 of the cutting blade 44 plus the portion of ring cap 68 engaging counterbore 66. Similarly, the diameter of counterbore 62 is slightly greater than the diameter of the mid-section 74 of the cutting blade 44, and the length of counterbore 62 is slightly greater than the length of the mid-section 74 of the cutting blade 44 plus the portion of ring cap 68 engaging counterbore 66.
Thus, in the assembled cross-sectional configuration shown in FIG. 3, a plastic inner core 50 extends in sliding relation through the majority of the outer sheath 42. At the distal end of the plastic core, the stainless steel core 52 is rigidly and co-axially attached to the plastic core 50 and extends distally and rigidly outwardly from the distal end 54 of the outer sheath 42.
The cutting blade 44 receives the stainless steel core 52 in sliding relationship while at the same time being disposed in the xe2x80x9cfloatingxe2x80x9d relationship with respect to the counterbores 62, 64 and 66 as discussed above. This has been found to partially alleviate alignment problems arising from the cutting blade edge engaging the outer blood vessel wall while the distal recess wall engages the inner blood vessel wall, but at the expense of several further trade-offs.
Since the cutting blade is allowed to xe2x80x9cfloatxe2x80x9d, it is not possible to perform the punching operation by slicing the tissue by the relative rotation of the outer sheath and the inner core structure. Further, the problems inherent in misalignment (and hence a dragging frictional engagement) between the cutting blade and the inner core remains, as do those associated with the complexity and expense of insert molding a plastic inner core in co-axial relationship to a metallic core passing through the cutting blade.
In addition, surgeons have experienced difficulty in removing punched out tissue plugs from the main body/cutter blade of conventional surgical punch devices. This is important because a surgeon typically desires to form a plurality of holes in the aorta at substantially the same point in a multiple heart by-pass surgical procedure. Hence, difficulty and/or delay in clearing the punch of previously punched out tissue is undesirably time-consuming and frustrating, particularly in the time-sensitive context of open-heart surgical procedures. The reasons for these problems will appear below in connection with alternative embodiments of the invention designed to alleviate or remove them from the operational characteristics of the novel surgical punch device herein described and claimed.
Accordingly, it is an object of the present invention to provide a surgical punch device wherein the cutting mechanism and the activation mechanism are distinct but interconnected elements, and the entire cutting mechanism is self-aligning relative to both the activation mechanism and the tissue to be punched.
It also is an object of the present invention to provide a surgical punch device that provides a smooth edged cut without the distraction of noticeable rubbing or catching between the parts thereof and/or with tissue.
Further, it is another object of the invention to provide a surgical punch device wherein the cutting blade and the anvil/support carrying inner core portions of the cutting mechanism respectively xe2x80x9cfloatxe2x80x9d separately relative to the outer sheath and inner rod of the activation mechanism.
Still further, it is an object of the above invention to provide a surgical punch device that may be made either in a disposable or in a re-usable form according to the preference of the user, cost considerations and/or the desired robustness of construction among other factors.
Yet another object of the invention is to provide a surgical punch device having an improved cutting blade designed for piercing tissue to be removed by the surgical punching device at preselected circumferentially spaced locations about the plug of tissue to be punched out prior to shearing the circumferential tissue located along the desired plug periphery between the pierced locations.
Still another object of the invention is to provide a surgical punch device wherein rough and/or frayed edges of a punched out plug do not interfere with the ease of removal of a punched out tissue plug from the interior of the surgical punch device.
In summary, a device for forming openings in internal bodily tissue such as blood vessels or the like during the course of surgical procedures such as by-pass surgery is provided. The device includes a cutting blade having a body portion defining a longitudinal passageway and a substantially distally facing cutting edge. The device also includes an inner core disposed in reciprocally sliding relationship with the passageway of the cutting blade. The inner core has a support portion at its distal end, and a tissue engagement portion located proximally adjacent to the distal support portion. In addition, an activation mechanism including an outer sheath and inner core, often in a generally syringe-like configuration, is provided for moving the cutting blade and the inner core generally co-axially relative to one another.
Specifically, the movement of the cutting blade and the inner core is contemplated to be between a first position wherein the distal portion of the core extends distally of the cutting edge of the cutting blade, and a second position wherein the distal portion of the core resides within the passageway of the cutting blade. The passageway of the cutting blade and the inner core are sized relative to one another such that a plug of tissue received by the tissue engagement portion may be sheared away from the adjoining tissue as the inner core and cutting blade are moved from their first relative positions to their second relative positions.
In addition, the inner core and cutting blade are respectively attached to different reciprocally moving portions of the activation mechanism. This connection is made in such a manner that the respective longitudinal axes of the cutting blade passageway and the outer sheath portion of the syringe-like activation mechanism on the one hand, and the inner core member and the plunger portion of the activation mechanism on the other hand may substantially freely deviate (i.e., xe2x80x9cfloatxe2x80x9d) to a limited extent relative to one another as the core member and the cutting blade are moved from their first relative positions to their second relative positions by manipulation of the activation assembly.
More specifically, the present invention proceeds from the realization that it is the relationship of the cutting blade and the inner core extending therethrough so as to directly interact with the cutting blade that controls the ultimate functional characteristics and results of the use of a surgical punch device. In particular, it is interactions between portions of the device at locations removed from the cutting blade/inner core mechanism that cause the problems referred to above in the cut away of a tissue plug from a tissue layer. Hence, it has been found that a surgical punch device may be accurately characterized as a combination of an activation mechanism including syringe-like components with a separate cutting apparatus including a co-axially aligned cutting blade and reciprocally movable core member. Further, it has been found that by modifying a conventional surgical punch in accordance with this novel characterization, a significantly improved device results.
Accordingly, the foregoing and other objects, features and advantages of the present invention are accomplished by the provision of a substantially conventional surgical punch device in which the attachment of a tissue receiving core portion extending through the cutting blade is modified so as to allow the core portion to xe2x80x9cfloatxe2x80x9d relative to its attachment to the distal end of the plunger-like portion of the activation assembly. In this way, the core portion and the cutting blade of what sometimes will be referred to hereinafter as the xe2x80x9ccutting assemblyxe2x80x9d may be disposed in separate so-called xe2x80x9cfloatingxe2x80x9d relationships to the respective longitudinal axes defined by the outer sheath and the inner plunger-like portions of the activation assembly. This, in turn, leads to the avoidance of the phenomenon of a dragging resistance experienced by users of prior versions of surgical punch devices both with, and without, xe2x80x9cfloatingxe2x80x9d cutting blades. In addition, the resulting device is more easily operated, and the resulting punched hole in tissue is more accurately and cleanly cut.
Also, in some embodiments, a substantially triangular cross-sectional portion of the distal portion of the outer anvil/support wall at its outer periphery may be removed. By so doing, the outer anvil/support wall becomes close to pointed at its proximal end and tapers inwardly as it extends from its proximal end toward its distal end. This configuration presents less resistance to the passage of the tissue stretched during the punching operation discussed above. It also provides a channel-like cavity into which the previously stretched tissue can collect without causing binding against the inner wall of the cutting blade as the core is moved distally relative to the cutting blade to free a previously cut tissue plug. Therefore, more previously stretched tissue can work its way between the anvil/support and the inner cutting blade wall as the core is moved distally relative thereto. Also, the previously stretched tissue that heretofore tended to bunch up at the distal end of the gap between the anvil/support and the inner cutting blade wall is provided with room within which to gather in a manner that does not exert significant resistance against the inner cutting blade wall.
Similarly, the diameter of the distally facing ledge of the main portion of the metal core that forms a wall of the recessed portion may be reduced and the outer wall of the main portion of the metallic core gradually tapered (or more sharply tapered) proximally and outwardly from the periphery of the so reduced diameter of the distally facing ledge. In this embodiment, the tapering continues until the outer wall of the main portion of the metal core reaches its original diameter (i.e., generally slidingly engaging the inner wall of the outer sheath/cutting blade).
The latter configuration provides an open, substantially triangular cross-sectioned channel into which tissue that formerly caused binding between the machined metal core and the inner wall of the cutting blade may collect. In this manner, rough and/or ragged tissue plug edges are prevented from introducing undesirable resistance to the free distal movement of the metal core relative to the inner wall of the cutting blade for the removal of punched out tissue from the interior of the tool. Still further, the addition of a surgically inert lubricating or friction reducing coating material onto the distally extending portion of the main machined metal core is contemplated as an option to further reduce sticking.
Additional embodiments of the invention also are contemplated. In one such embodiment, the distal cutting edge of the cutting blade is formed as four or more cut away sections substantially equally spaced relative to one another along the circumference of the cutting edge. More particularly, starting from the conventional circular cutting edge disposed in a plane perpendicular to the axis of the cutting blade, a preselected number of point locations may be selected, usually in substantially equally spaced relation to one another about the periphery of the cutting edge. Thereafter, material may be removed from the cutting blade element between the preselected points such that corresponding new curved cutting blades are formed between each pair of preselected points. Each of the corresponding new curved cutting blades follows the inner wall of the cutting blade element in circumferential relation to the cutting blade as well as a corresponding curve in axial relation to the cutting blade.
In this way what may be referred to as a scalloped cutter blade edge may be created at the distal end of the cutting blade, with each scallop being the same as those adjacent thereto. The concept of this embodiment is that the various points will tend to pierce the tough and resilient tissue layer of the aorta wall, and that the cutting edges between the points thereafter will sever the aorta wall tissue layers between the pierced locations. Hence, the aorta wall tissue will be more accurately and cleanly severed, rather than stretched, by the cutting blade assembly. Also, the tissue plugs will be punched out with cleaner edges under the exertion of less applied force. Still further, a cutting edge similar to that just described may be formed along the outer proximal edge of the anvil either alone, or in combination with, the above-described cutting blade configuration, if desired.